英语句子成分－主语讲解 什么是主语？

主语相当于句子的话题或主题，即要说明的人或物。主语一般位于句首，且不能省略。但在某些特定的句式里，如：疑问句倒装句祈使句感叹句等，句子主语也可以位于谓语动词之后或省略。【想一想】哪些词类或短语可以用作主语？（答：能用来做主语的有：名词、代词、数词、动名词或动名词短语、动词不定式或动词不定式短语、主语从句等。）

1.名词（或名词词组）

My pen　is　green. (单数可数名词)

Jane is an American girl. (专有名词)

2.代词

I am a student. (主格人称代词)

Her pen is blue, and mine is red.（名词性物主代词）

These are my books. (指示代词)

Who is not here today? (疑问代词)

Nothing was wrong with his eyes. (不定代词)

3.数词

Two and one is three. (基数词)

The second was a tall man. (序数词)

4.动名词

Eating too much is bad for your health. (动名词)

Playing games is much better than staying at home. (动名词短语)

5.形容词

The rich are not always happy.(少数形容词前边加the 相当于名词)

6.动词不定式

To see is to believe.(动词不定式)

It will take you 2 hours to get to the station.(it作形式主语，动词不定式短语作真正主语)

7.主语从句（仅作了解）

What the teacher said yesterday is important.

△几个常见加the后可以名词化的形容词是：poor, rich, young, old，happy,blind, beautiful等。

△主语和谓语的顺序有两种：（1）自然顺序，即主语在前，谓语在后；（2）倒装语序，即谓语或谓语的一部分在前， 主语位于其后。例如：

Are you a student？

Do you like English songs?

What do you speak?

There is a bird in the tree. (there be 句型)

Here is your pen. (以副词here/there开头的句子习惯上主谓倒装)

There stands a policeman.